Traditional light conveyor belts are generally constructed from fabrics coated by plastics or rubber, or plastic sheets. In applications where hygiene and cleanliness are important, such as food processing plants, these conveyor belts are preferably made from monolithic plastics or otherwise sealed such that no contaminants can enter into the body of the belt, in order to prevent bacterial growth and other hygienic issues. Additionally, cleaning systems, which spray cleaning fluid on the sprockets and belts of such conveyors, are used to prevent the spread of contaminants.
Such conveyor belts are generally provided with transverse ribs on the underside of the belt in order to allow drive sprocket(s) to engage the ribs and better propel the belt. FIG. 9 shows the current art of drive sprocket used to engage the ribs of a belt and drive the belt (see, e.g., U.S. Patent Application Publication No. 2006/0144676). As can be seen in FIG. 9, current sprockets a generally cylindrical in shape and have grooves which engage the ribs of the belt.
However, a sprocket as described above suffers from several disadvantages in environments where cleaning systems are used to maintain hygiene. First, the belt sits tightly on the sprocket, leaving little to no gap between the sprocket and the underside of the belt. In this case, debris and contaminants are squeezed into the small gaps causing great difficulty in cleaning the affected areas. Additionally, in many cases, two or more sprockets are used to engage a belt, and the above-described sprockets offer few options for passing cleaning fluid to the area between sprockets.
These disadvantages have been overcome for modular belts by the sprocket depicted in FIG. 7A in conjunction with the cleaning-in-place system pictured in FIG. 8 (see, e.g., U.S. Patent Application Publication Nos. 2008/0190462 and 2990/0050185). However, the sprocket of FIG. 7A is not ideally suited for use with flexible (non-modular) belts. For example, as depicted in FIG. 7B, the shape of the teeth, and lack of support between adjacent pairs of teeth, allow a flexible belt to buckle as it is forced around the periphery of the sprocket while the belt is under tension. Over time, this buckling causes damage to the belt including cracks on the surface of the belt.
Accordingly, there is a need for an improved sprocket for use with flexible belts and that avoids the above-described shortcomings.